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1、摘要在聲波測井中,常常會因為地層的衰減,使得聲波測井儀無法接收聲波的首波信號。為了增強接收的聲波信號,通常采用兩種方法:一是通過增大換能器尺寸來降低聲波的頻率從而減小地層衰減;二是增大換能器的發(fā)射功率來增大聲波信號的功率,但是由于換能器所能承受的最大激發(fā)電壓和溫度的限制,致使發(fā)射聲信號功率有限。所以,可以通過相控陣技術(shù)使陣列發(fā)射探頭發(fā)出的聲信號同相位疊加,改善指向性達到增強首波信號的目的。陣列聲波測井儀有兩種組成方式:一是單接收器和一維陣列聲源的組合;二是單聲源和一維陣列接收器的組合。換能器為薄圓管形壓電換能器。本文采用了聲波測井中的傳輸網(wǎng)絡(luò)理論與指向性權(quán)系數(shù)的概念,推導(dǎo)出了換能器的幾何形
2、狀與尺寸對線陣聲源的導(dǎo)向系數(shù)的關(guān)系。通過改變陣列接收器接收到的聲波信號的時間偏移量和線陣聲源的激發(fā)延遲時間,可以令接收的首波幅度(陣列聲源)與疊加波的首波幅度(陣列接收器)達到最大。通過本文提出的方法可以令聲波測井中接收到的聲波測井信號的首波幅度大大增加。關(guān)鍵詞:陣列聲波測井、相控陣、指向性、換能器、激發(fā)延遲時間25AbstractInacousticlogging,oftenbecauseofthedeclineofformationmakessonictoolcannotreceivethefirstwaveofsoundwavesignal.Inordertoenhancethere
3、ceivedacousticsignal,usuallyadoptstwomethods:oneisthroughincreasedtoreducethefrequencyoftheacoustictransducerdimensionreducingformationattenuation;Secondistoincreasethetransmissionpowerofthetransducertoincreasetheacousticsignalofpower,butbecauseofthetransducercanbearthelimitofmaximumexcitationvolt
4、ageandtemperature,thesoundemissionsignalpowerco.,LTD.Socanmakethroughphasedarraytechnologyemissionprobearrayacousticsignalswiththephasesuperposition,achievetheenhancementpurposetothefirstwavesignaltoimprovethedirectivity.Arrayacousticloggingtooliscomposedoftwoways:oneisthecombinationofsinglereceiv
5、erandaone-dimensionalarraysource;Thesecondissimplesoundsourceandthecombinationofaone-dimensionalarrayreceiver.Transducerisathincirculartubeintheshapeofapiezoelectrictransducer.Thispaperadoptsthetransmissionnetworktheoryanddirectivityofacousticloggingweightcoefficient,theconceptofthegeometricshapea
6、ndsizeofthetransducerisdeducedontherelationshipbetweenthelineararraydirectionGuidecoefficientofsoundsource.Bychangingthearrayreceivertoreceivethetimeoffsetandlineararrayacousticsignalsourceexcitationdelaytime,canreceivethefirstwaveofsoundsource(array)andsuperpositionofwaveamplitudeofthefirstwaveam
7、plitude(arrayreceiver)maximum.Bytheproposedapproachcanmakesoniclogginginthereceivedthefirstwaveofacousticloggingsignalamplitudeincreasegreatly.Keywords:arraysoniclogging、phasedarray、directivity、transduc、Stimulate